Attachment 7 - Flood Impact Assessment - Covey · 132005.638.06

         4.0     CONCLUSION
         Covey Associates has been engaged by Noosa Shire Council to provide a Flood Impact Assessment for the
         staged development of the proposed Doonan Landfill redevelopment and its facilities and associated
         infrastructure at 561 Noosa-Eumundi Rd, Doonan.

         Ensemble storm hydraulic (TUFLOW) flood modelling in accordance with ARR 2019 guidelines was
         undertaken for all existing and developed case scenarios for the 50%, 10%, 1% and 1% climate change
         Annual Exceedance Probability (AEP) events. For the ultimate developed case scenario (Stage 6),
         additional modelling was undertaken for the 0.5%, 0.2%, and 0.1% AEP events to determine future
         building floor levels.

         The flood mapping demonstrated that generally the on-site overland flow paths adequately conveyed
         both internal and external catchment flows. Increases in water surface level were noted in the developed
         case scenarios, however, all increases were contained within existing flow paths and at road crossings
         there was no worsening of the existing hazard category for these areas. Further, as a result of the
         proposed development, there is no actionable nuisance due to the change in peak water level, depth,
         velocity and hazard on the surrounding properties for all modelled AEPs.

         Through this assessment, it has been demonstrated that the proposed development and associated
         infrastructure will not result in any actionable nuisance to any of the surrounding properties or
         infrastructure with regards to overland flow. Further, based on the results of this study, on-site detention
         is not required for the development.

         Sufficient consideration of stormwater quantity controls has been demonstrated by:
             •        Compliance with the requirements of the Noosa Plan (2020);
             •        Queensland State Planning Policy (2017); and
             •        Compliance with QUDM (2017).




Flood Impact Assessment                                                                                      Page 19 of 25
Project No 244035 | Ref No M25-0479Rpt – Issue A – January 2026